Process for the solvent-free, continuous preparation of polyureas

ABSTRACT

The invention relates to a process for the solvent-free, continuous preparation of polyureas by reacting at least one isocyanate and/or isocyanurate having at least two NCO groups with at least one diamine and/or polyamine in an extruder, intensive kneader, intensive mixer or static mixer by thorough mixing and rapid reaction by briefly heating and subsequent cooling to isolate the end product.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention relates to a process for the solvent-free,continuous preparation of polyureas by reacting at least onediisocyanate and/or isocyanurate with at least one diamine in anextruder, intensive kneader, intensive mixer or static mixer by thoroughmixing and brief reaction by heating and subsequent isolation of the endproduct by cooling.

[0003] 2. Description of the Related Art

[0004] Polyureas are disclosed in EP 1 184 399. They are prepared insolvents, as described therein. A disadvantage of this preparationmethod is that the batchwise preparation of the desired product polyureain the solvent toluene is very time-consuming and energy inefficient,since the product has to be dried for several hours at elevatedtemperatures under reduced pressure. The method described is anextremely inconvenient and expensive one for the industrial productionof polyureas.

[0005] It is an object of the present invention to provide a novelprocess for the preparation of polyureas, which does not have thedisadvantages of the prior art.

[0006] Surprisingly, it was found that polyureas can be prepared rapidlyand in an uncomplicated manner in an extruder, intensive kneader,intensive mixer or static mixer.

[0007] The present invention relates to a process for the solvent-free,continuous preparation of polyureas by reacting at least one isocyanateand/or isocyanurate having at least two NCO groups with at least onediamine and/or polyamine in an extruder, intensive kneader, intensivemixer or static mixer by thorough mixing and rapid reaction by brieflyheating and subsequent isolation of the end product by cooling.

[0008] The principle of the process is that the reaction of thereactants is carried out continuously in an extruder, intensive kneader,intensive mixer or static mixer by thorough mixing and rapid reaction bybriefly heating.

[0009] Temperatures of from 10 to 325° C. are used in the process, thetemperature varying, as shown in the examples, depending on the product.

[0010] The residence time of the starting materials in the abovementioned units is usually from 3 seconds to 15 minutes, preferably from3 seconds to 5 minutes, particularly preferably from 5 to 180 seconds.The reactants are rapidly reacted by briefly heating at temperatures offrom 25 to 325° C., preferably from 50 to 250° C., very particularlypreferably from 70 to 220° C. Depending on the nature of the startingmaterials and of the final products, these values for residence time andtemperature may also have other preferred ranges.

[0011] It is possible to discharge continuously the resulting,homogeneous, generally crumbly material. Optionally, a continuoussubsequent reaction may be carried out, otherwise the hot product iscooled (e.g. on a cooling belt) and further compounded (e.g. milled), ifrequired.

[0012] Extruders, such as single-screw or multiscrew extruders, inparticular twin-screw extruders, planetary roller extruders or annularextruders, intensive kneaders, intensive mixers, such as Turrax mixers,or static mixers are particularly suitable as units for the processaccording to the invention and are preferably used.

[0013] It was surprising that the reaction, which requires several hoursin the batchwise process, takes place essentially to completion in a fewseconds in the units. In addition, the product is obtained in solid,more or less granular form and can, after cooling is complete, be fedfor further working-up (e.g. milling) or directly for storage (e.g.silo) or packing (e.g. bagging). The basic principle is the fact that abrief application of heat in conjunction with the mixing effect of theunit (e.g. intensive kneader) is sufficient to convert the reactantscompletely or substantially completely. By suitable equipping of themixing chambers or assembly of the screw geometries, intensive kneaderspermit rapid thorough mixing with simultaneous intense heat exchange. Onthe other hand, uniform flow in the longitudinal direction with asuniform a residence time as possible is also ensured. Moreover,different amounts of heat in the individual apparatus housings orsections may be generated.

[0014] The reactants are metered into the units as a rule in separatereactant streams. In the case of more than two reactant streams, theymay also be combined before being fed in. The material streams may alsobe divided and fed to the units in different amounts at differentpoints. In this way, specific concentration gradients are established,which results in complete reaction. The entry points and time of entryof the reactant streams in the sequence may be varied.

[0015] For preliminary reaction and/or completion of the reaction, aplurality of units may also be combined.

[0016] The cooling following the rapid reaction can be integrated in thereaction part, in the form of a multizone embodiment, as in the case ofextruders or Contema machines. It is also possible to use: tube bundles,pipe coils, chillrolls, air conveyors and conveyor belts of metal.

[0017] The end product may be compounded by being first brought to asuitable temperature by further cooling by appropriate means above,depending on the viscosity of the end product leaving the intensivekneader zone or the postreaction zone. Pelletizing or comminution of theend product to a desired particle size is then carried out by means ofcrushing rolls, a pinned disk mill, a hammer mill, an air separationball mill, a flaking mill or the like.

[0018] All known aliphatic, cycloaliphatic, araliphatic and aromaticisocyanates having at least two NCO groups and the isocyanurates thereofin pure form or as mixtures with one another, may be used for thepreparation of the polyureas. The following may be mentioned by way ofexample: cyclohexane diisocyanates, methylcyclohexane diisocyanates,ethylcyclohexane diisocyanates, propylcyclohexane diisocyanates,methyldiethylcyclohexane diisocyanates, phenylene diisocyanates,tolylene diisocyanates, bis(isocyanatophenyl)methane, propanediisocyanates, butane diisocyanates, pentane diisocyanates, hexanediisocyanates (e.g. hexamethylene diisocyanate (HDI) or1,5-diisocyanato-2-methylpentane (MPDI)), heptane diisocyanates, octanediisocyanates, nonane diisocyanates (e.g.1,6-diisocyanato-2,4,4-trimethylhexane and1,6-diisocyanato-2,2,4-trimethylhexane (TMDI)), nonane triisocyanates(e.g. 4-isocyanatomethyl-1,8-octane diisocyanate (TIN)), decane di- andtriisocyanates, undecane di- and triisocyanates, dodecane di- andtriisocyanates, isophorone diisocyanate (IPDI),bis(isocyanatomethyl-cyclohexyl)methane (H₁₂MDI),isocyanatomethyl-methylcyclohexyl isocyanates,2,5(2,6)bis(isocyanatomethyl)bicyclo[2.2.1]heptane (NBDI),1,3-bis(isocyanatomethyl)cyclohexane (1,3-H₆-XDI) and1,4-bis(isocyanatomethyl)cyclohexane (1,4-H₆-XDI). The list does ofcourse include all regioisomers and stereoisomers of the isocyanatesmentioned by way of example. HDI, IPDI, MPDI, TMDI, 1,3- and 1,4-H₆-XDI,NBDI and mixtures of HDI and IPDI are preferably used. Preferredpolyureas in the context of the invention are those which consist ofIPDI, IPDI-isocyanurate, HDI or HDI-isocyanurate and any desiredmixtures thereof.

[0019] All aliphatic, (cyclo)aliphatic, cycloaliphatic and aromaticdiamines and/or polyamines (C₅-C₁₈) can be used in the invention.

[0020] Diamines which are suitable in principle are 1,2-ethylenediamine,1,2-propylenediamine, 1,3-propylenediamine, 1,2-butylenediamine,1,3-butylenediamine, 1,4-butylenediamine, 2-(ethylamino) ethylamine,3-(methylamino)propylamine, 3-(cyclohexylamino)propylamine,4,4′-diaminodicyclohexylmethane, isophoronediamine,4,7-dioxadecane-1,10-diamine, N-(2-aminoethyl)-1,2-ethanediamine,N-(3-aminopropyl)-1,3 -propanediamine,N,N″-1,2-ethanediylbis(1,3-propanediamine) and hexamethylenediamines,which may also carry one or more C₁-C₄-alkyl radicals. Mixtures of saiddiamines can also be used. Isophoronediamine is preferably used.

[0021] Polyamines such as, for example, 4-aminomethyl-1,8-octanediamine,diethylenetriamine, dipropylenetriamine, triethylenetetramine andtetraethylenepentamine can also be used.

[0022] In general, polyureas having an NCO/NH₂ ratio of 0.8 to 1.2:1 areprepared. With the use of equimolar amounts having an NCO/NH₂ ratio of1:1, infinitely crosslinked, solid and brittle polymers which melt onlyabove 240° C. with decomposition and are insoluble in solvents areobtained.

[0023] Preferred polyureas in the context of the invention are thosewhich consist of IPD and IPDI and/or IPDI-isocyanurate and/or HDI and/orHDI-isocyanurate. These have molar masses of more than 4000 and containat least 8% by weight, preferably 20% by weight, particularly preferablyfrom 40 to 100% by weight, of isocyanurates and/or amines having afunctionality of >2, preferably isocyanurates, preferably IPDI- and/orHDI-isocyanurate. Polyureas obtained from pure isocyanurates and IPD arealso preferred.

[0024] The subject of the invention is explained below with reference toexamples.

EXAMPLES

[0025] 1. Preparation of Polyurea by Reacting a Solution ofIPDI-isocyanurate in Isophorone Diisocyanate (IPDI) WithIsophoronediamine (IPD)

[0026] The polyurea is prepared from a mixture of 40% by weight ofIPDI-isocyanurate and 60% by weight of IPDI as isocyanate component andIPD as amine.

[0027] The molar ratio of NCO groups to NH₂ groups is 3.00:3.20. Bothmaterial streams are fed in liquid form into a twin-screw extruderhaving corotating screws. The extruder has barrels which are separatelytemperature-controllable (heatable and coolable).

[0028] Barrel 1 is operated at room temperature. Two following barrelsare heated to 25 to 60° C. and further following barrels aretemperature-controlled at 80 to 180° C. The temperature at which theproduct emerges is from 130 to 180° C.

[0029] The isocyanate mixture is metered into barrel 1 at a rate of 8.95kg/h. The diamine IPD is added to barrel 3 with a throughput of 5.04kg/h. The extruder speed is from 100 to 250 rpm. The emerging, white,crumbly product is cooled on a cooling belt.

[0030]2. Preparation of Polyurea by Reacting HDI-isocyanurate WithIsophoronediamine (IPD)

[0031] The molar ratio of NCO groups to NH₂ groups is 1.00:1.00. Bothmaterial streams are fed in liquid form into a twin-screw extruderhaving corotating screws. The extruder has barrels which are separatelytemperature-controlled (heatable and coolable).

[0032] Barrel 1 is temperature-controlled at from 60 to 90° C. Barrel 2is heated to 100 to 190° C. and three following barrels aretemperature-controlled at from 200 to 310° C. There follow two barrels,which are operated at from 130 to 310° C. The temperature at which theproduct emerges is from 170 to 220° C.

[0033] The isocyanate mixture is metered into barrel 1 at a rate of 4.07kg/h. A pressure control valve adjusted to 8 to 10 bar is required. Thediamine IPD is added to barrel 3 with a throughput of 1.78 kg/h.

[0034] The extruder speed is from 150 to 250 rpm.

[0035] The emerging, white, crumbly product is cooled on a cooling belt.

[0036] 3. Preparation of Polyurea by Reacting IPDI-isocyanurate WithIsophoronediamine (IPD)

[0037] The molar ratio of NCO groups to NH₂ groups is 3.00:3.40. Theextruder has barrels which are separately temperature-controlled(heatable and coolable).

[0038] Barrel 1 is temperature-controlled at from 25 to 60° C. Barrel 2is heated to 70 to 120° C. and the following three barrels aretemperature-controlled at from 160 to 190° C. There follow two barrels,which are operated at 110 to 180° C. The temperature at which theproduct emerges is from 120 to 170° C.

[0039] The isocyanurate is metered into barrel 1 in the form of a coarsepowder at a rate of 4.04 kg/h. The diamine IPD is added in liquid formto barrel 4 with a throughput of 0.83 kg/h.

[0040] The extruder speed is from 75 to 225 rpm. The emerging, whitesolid is cooled on a cooling belt.

[0041] DE 10221047.0, May 10, 2002, is hereby incorporated by reference.

1. A process for the solvent-free, continuous preparation of polyureascomprising: reacting at least one compound selected from the groupconsisting of isocyanate(s) having at least two NCO groups andisocyanurate(s) having at least two NCO groups, and mixtures thereof,with at least one compound selected from the group consisting ofdiamine(s) and polyamine(s), and mixtures thereof, in an extruder,intensive kneader, intensive mixer or static mixer by thorough mixingand rapid reaction by briefly heating and subsequent cooling to isolatethe end product.
 2. The process as claimed in claim 1, wherein theisocyanate(s) and isocyanurate(s) is/are selected from the groupconsisting of aliphatic, cycloaliphatic, araliphatic and aromatic,isocyanates and isocyanurates, and mixtures thereof.
 3. The process asclaimed in claim 1, wherein the diamine(s) and polyamine(s) is/areselected from the group consisting of cyclohexane diisocyanates,methylcyclohexane diisocyanates, ethylcyclohexane diisocyanates,propylcyclohexane diisocyanates, methyldiethylcyclohexane diisocyanates,phenylene diisocyanates, tolylene diisocyanates,bis(isocyanatophenyl)methane, propane diisocyanates, butanediisocyanates, pentane diisocyanates, hexane diisocyanates, such ashexamethylene diisocyanate (HDI) or 1,5-diisocyanato-2-methylpentane(MPDI), heptane diisocyanates, octane diisocyanates, nonanediisocyanates, such as 1,6-diisocyanato-2,4,4-trimethylhexane or1,6-diisocyanato-2,2,4-trimethylhexane (TMDI), nonane triisocyanates,such as 4-isocyanatomethyl-1,8-octane diisocyanate (TIN), decane di- andtriisocyanates, undecane di- and triisocyanates, dodecane di- andtriisocyanates, isophorone diisocyanate (IPDI),bis(isocyanatomethyl-cyclohexyl)methane (H₁₂MDI),isocyanatomethyl-methylcyclohexyl isocyanates,2,5(2,6)-bis(isocyanatomethyl)bicyclo[2.2.1]heptane (NBDI),1,3-bis(isocyanatomethyl)cyclohexane (1,3-H₆-XDI) or1,4-bis(isocyanatomethyl)cyclohexane (1,4-H₆-XDI), and the isocyanuratesthereof, and mixtures thereof.
 4. The process as claimed in claim 1,wherein the isocyanate(s) and isocyanurate(s) is/are selected from thegroup consisting of isophorone diisocyanate (IPDI), hexamethylenediisocyanate (HDI), the isocyanurates thereof, and mixtures thereof. 5.The process as claimed in claim 1, wherein the diamine(s) is/are analiphatic, a cycloaliphatic, an araliphatic or aromatic diamine(s), ormixtures thereof.
 6. The process as claimed in claim 1, wherein thediamine(s) is/are 1,2-ethylenediamine, 1,2-propylenediamine,1,3-propylenediamine, 1,2-butylenediamine, 1,3-butylenediamine,1,4-butylenediamine, 2-(ethylamino)ethylamine,3-(methylamino)propylamine, 3-(cyclohexylamino)propylamine,4,4′-diaminodicyclohexylmethane, isophoronediamine,4,7-dioxadecane-1,10-diamine, N-(2-aminoethyl)-1,2-ethanediamine,N-(3-aminopropyl)-1,3-propanediamine,N,N″-1,2-ethanediylbis(1,3-propanediamine) and hexamethylenediamines,which may be substituted by one or more C₁-C₄-alkyl radicals, ormixtures thereof.
 7. The process as claimed in claim 1, comprising IPDIand isophoronediamine (IPD).
 8. The process as claimed in claim 1,comprising an isocyanurate of IPDI and IPD.
 9. The process as claimed inclaim 1, comprising a mixture of IPDI and IPDI-isocyanurate and IPD. 10.The process as claimed in claim 1, comprising HDI and IPD.
 11. Theprocess as claimed in claim 1, comprising an isocyanurate of HDI andIPD.
 12. The process as claimed in claim 1, comprising a mixture of HDIand HDI-isocyanurate and IPD.
 13. The process as claimed in claim 1,comprising a mixture of IPDI- and HDI-isocyanurate and IPD.
 14. Theprocess as claimed in claim 1, wherein the reaction is carried out withan NCO/NH₂ ratio of 0.8 to 1.2:1.
 15. The process as claimed in claim 1,wherein the reaction is carried out in a single-screw, twin-screw ormultiscrew extruder, annular extruder or planetary roller extruder. 16.The process as claimed in claim 1, wherein the reaction is carried outin a twin-screw extruder.
 17. The process as claimed in claim 1, whereinthe reaction is carried out in an intensive mixer or intensive kneader.18. The process as claimed in claim 1, wherein the reaction is carriedout in a static mixer.
 19. The process as claimed in claim 1, whereinthe reaction is carried out in an extruder, intensive kneader, intensivemixer or static mixer having a plurality of identical or differenthousings which can be thermally controlled independently of one another.20. The process as claimed in claim 1, wherein the temperature in theextruder, intensive kneader, intensive mixer or static mixer is from 10to 325° C.
 21. The process as claimed in claim 1, wherein, byappropriate equipment in the mixing chambers and design of the screwgeometry, the extruder or intensive kneader firstly gives rapid,thorough mixing and rapid reaction with simultaneous intense heatexchange and, secondly, produces uniform flow in the longitudinaldirection with a uniform residence time.
 22. The process as claimed inclaim 1, wherein the reaction is carried out in the presence ofcatalyst(s) and/or additive(s).
 23. The process as claimed in claim 1,wherein starting materials and/or catalyst(s) and/or additive(s) are fedtogether or in separate reaction streams, in liquid or solid form, tothe extruder, intensive kneader, intensive mixer or static mixer. 24.The process as claimed in claim 23, wherein additive(s) are combinedwith starting materials to give one reactant stream.
 25. The process asclaimed in claim 23, wherein, if there are more than two reactantstreams, these are combined before being fed in.
 26. The process asclaimed in claim 23, wherein one or both reactant streams are divided.27. The process as claimed in claim 23, wherein catalyst(s) is/arecombined with one of the reactant streams, or is initially introduced insolution in one of the streams.
 28. The process as claimed in claim 23,wherein additive(s) is/are combined with one of the reactant streams, oris initially introduced in solution in one of the streams.
 29. Theprocess as claimed in claim 23, wherein the entry points of the reactantstreams in the sequence can be varied and can be offset timewise. 30.The process as claimed in claim 1, wherein a post-reaction is carriedout.
 31. The process as claimed in claim 30, wherein the post-reactionis carried out in a continuously operated system.
 32. The process asclaimed in claim 1, wherein a compounding is first initiated afterfurther cooling to a temperature sufficient for subsequent filling/silostorage, depending on the viscosity of the product leaving the extruder,intensive kneader, intensive mixer or static mixer and/or apost-reaction zone.
 33. The process as claimed in claim 1, wherein aresidence time of reactant materials is from 3 seconds to 15 minutes.34. The process as claimed in claim 1, wherein the reaction takes placeat temperatures of from 25 to 325° C.
 35. A polyurea obtained bysolvent-free, continuous reaction of at least one isocyanate and/orisocyanurate having at least two NCO groups with at least one diamineand/or polyamine in an extruder, intensive kneader, intensive mixer orstatic mixer by thorough mixing and rapid reaction by briefly heatingand subsequent cooling to isolate the end product.
 36. The process asclaimed in claim 30, wherein the post-reaction is carried out in atubular reactor, a stirred or unstirred dwell tank or a tube bundle. 37.The process as claimed in claim 1, wherein a residence time of reactantmaterials is from 3 seconds to 5 minutes.
 38. The process as claimed inclaim 1, wherein a residence time of reactant materials is from 5 to 180seconds.
 39. The process as claimed in claim 1, wherein the reactiontakes place at temperatures from 50 to 250° C.
 40. The process asclaimed in claim 1, wherein the reaction takes place at temperaturesfrom 70 to 220° C.